16 Aquarii
Star in the constellation Aquarius
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16 Aquarii, abbreviated 16 Aqr, is a star in the constellation of Aquarius. 16 Aquarii is the Flamsteed designation. It is a faint star, just visible to the naked eye, with an apparent visual magnitude of 5.869.[2] Based upon an annual parallax shift of 9.5 mas,[1] it is located about 342 light years away. It is moving closer to the Earth with a heliocentric radial velocity of â6 km/s,[5] and is predicted to come within 220 light-years in 6.8 million years.[4]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 21h 21m 04.31919s[1] |
| Declination | â04° 33â² 36.4532â³[1] |
| Apparent magnitude (V) | 5.869[2] |
| Characteristics | |
| Spectral type | G7 III[3] |
| BâV color index | 0.912±0.001[4] |
| Astrometry | |
| Radial velocity (Rv) | â6.0±2.9[5] km/s |
| Proper motion (μ) | RA: â9.86[6] mas/yr Dec.: +11.22[6] mas/yr |
| Parallax (Ï) | 9.5319±0.1192 mas[1] |
| Distance | 342 ± 4 ly (105 ± 1 pc) |
| Absolute magnitude (MV) | 1.08[4] |
| Details[7] | |
| Mass | 2.34±0.13 Mâ |
| Radius | 7.86±0.26 Râ |
| Luminosity | 37.4±2.3 Lâ |
| Surface gravity (log g) | 3.03±0.04 cgs |
| Temperature | 5,096±35 K |
| Metallicity [Fe/H] | 0.01±0.10 dex |
| Rotational velocity (v sin i) | 1.79[8] km/s |
| Age | 740±130 Myr |
| Other designations | |
| 15 Aqr, BDâ05°5524, HD 203222, HIP 105412, HR 8160, SAO 145317[9] | |
| Database references | |
| SIMBAD | data |
At the estimated age of 740 million years, this is an aging giant star currently on the red giant branch[7] with a stellar classification of G7 III.[3] This indicates it has exhausted the supply of hydrogen at its core and is generating energy via hydrogen fusion along a shell surrounding a hot core of inert helium. The star has 2.3 times the mass of the Sun and has expanded to 8 times the Sun's radius. It is radiating 37 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 5,096 K.[7]